Grinding tool fixture and method of manufacturing main body of grinding tool fixture

ABSTRACT

The present invention relates to a method of manufacturing a main body of a grinding tool fixture, a grinding tool fixture having a cap at a front, a sleeve and a coil spring consecutively connected, and a main body connected at a rear, and the main body having a body and a rotating shaft integrally formed with a rear of the body. The main body of the grinding tool fixture is turned, heat-treated, and then straightened. According to the present invention, a grinding tool for a grinder can be conveniently attached and detached by reciprocating a sleeve such that a separate working tool or fastener is not required, and the grinding tool can be immediately replaced even during use of the grinder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No. PCT/KR2017/007859, filed with the Korean Intellectual Property Office on Jul. 21, 2017, which claims priority to both Korean Patent Application No. 10-2016-0142393, filed on Oct. 28, 2016, and Korean Patent Application No. 10-2016-0142394, filed on Oct. 28, 2016, the entirely of all of which are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a grinding tool fixture and a method of manufacturing a main body of the grinding tool fixture, and more particularly, to a grinding tool fixture and a method of manufacturing a main body of the grinding tool fixture in which a grinding tool for a grinder may be conveniently attached and detached to and from an insertion groove of a grinding tool fixture by reciprocating a sleeve, the grinding tool may be immediately replaced even during use of the grinder, and straightness is ensured such that precise processing is possible.

BACKGROUND

Generally, after first processing of parts for automobile, shipbuilding, or various industries, second processing is required for not sufficiently processed portions, rough surfaces, or before painting. It is common to use a grinding machine that rotates grindstone at a high speed and precisely polishes an object when some degree of preciseness is required and use a hand grinder that is lightweight and easy to use to polish an object when a part does not require much preciseness.

A general hand grinder operates a rotating shaft at a high speed by an air pressure generated during operation of an electric motor or a compressor and uses a grinding tool mounted at the rotating shaft to grind a surface of an object to be grinded formed of timber, stone, metal, and the like, thereby polishing or sharpening not sufficiently processed portions, corners, recessed portions, or the like and performing finishing work.

As related art, according to a grinding holder attachment/detachment structure of a hand grinder of Korean Utility Model Registration No. 20-0376952, there is disclosed a grinding holder attachment/detachment structure of a hand grinder including a grinding holder (11) in which an insertion rod (18) having a grinding material (10) for processing an object mounted at one side and a recessed groove (18a) at the other side is formed, a coupling (13) having a recessed groove (21) and a through-hole (22) for accommodating the insertion rod (18) of the grinding holder (11) and a screw hole (24) fastened to a rotating shaft (12a) of a grinder main body (12) consecutively formed at a rear end thereof, an elastic member (14) accommodated between the through-hole (22) and the screw hole (24) of the coupling (13) and configured to provide a reaction force when the grinding holder (11) is attached and detached, a sleeve (15) mounted at a circumferential surface of the coupling (13) to be resiliently slidable, and a locking ball (16) disposed to lock and unlock the grinding holder (11) by being inserted into and withdrawn from the through-hole (22) formed at the center of the coupling (13) according to movement of the sleeve (15).

As another piece of related art, according to a device for attaching and detaching a grinding tool for a grinder of Korean Patent Registration No. 10-1056036, there is disclosed a device for attaching and detaching a grinding tool for a grinder, the device having a coupler mounted at a rotating shaft of a grinder main body and configured so that a grinding tool may be fixed and detached by sliding of a sleeve assembled to an outer circumferential surface of the coupler, the device including a grinding tool (11) having a grinding material (P1) mounted at one side of a body and a recessed groove (18a) disposed between a pair of flanges (17a, 17b) formed at a central portion of the other side, a coupler (12) having a seating hole (22a) into which the grinding tool (11) is fitted and fixed and a screw part (21b) including a through-hole (21a) and a locking step (21c) formed at a circumferential surface, a sleeve (13) disposed at the circumferential surface of the coupler (12), assembled to be resiliently slidable toward one side, and having a protruding piece (24) having an inclined surface (23a) and a step (23b) formed at an inner diameter part thereof, a locking ball (14) accommodated in the through-hole (21a) formed in the coupler (12) and configured to be inserted into and withdrawn from the recessed groove (18a) of the grinding tool (11) during movement of the sleeve (13) to fix and release the grinding tool (11), and a cap nut (16) fastened to a front end part of the coupler (12) and configured to regulate an assembling position of the sleeve (13), wherein an outer gear tooth part (18b) formed at a circumferential surface of a shaft extending toward a front end part at one side of the grinding tool (11) and an inner gear tooth part (22b) formed at an inner diameter part continuing from the seating hole (22a) of the coupler (12) are engaged with each other, the grinding tool (11) is separately formed of a first body (19A) having the grinding material (P1) and a second body (19B) having the outer gear tooth part (18b), and an axial rod (20b) formed at one end of the first body (19A) is configured to be bound to an insertion hole (20c) formed in the second body (19B).

However, in the above pieces of related art, a grinding tool for a grinder is attached and detached using a separate working tool or fastener, and there are disadvantages in that working time is delayed and vibration occurs during processing due to poor straightness of a main body of a grinding tool fixture.

Technical Problem

Therefore, the present invention has been devised to solve the above problems, and an objective of the present invention is to provide a grinding tool fixture and a method of manufacturing a main body of the grinding tool fixture in which a grinding tool for a grinder may be conveniently attached and detached by reciprocating a sleeve such that a separate working tool or fastener is not required, the grinding tool may be immediately replaced even during use of the grinder, and straightness is ensured such that precise processing is possible.

Technical Solution

The present invention relates to a method of manufacturing a main body of a grinding tool fixture, a grinding tool fixture (200) having a cap (30) at a front, a sleeve (40) and a coil spring (50) consecutively connected, and a main body (20) connected at a rear, and the main body (20) having a body (21) and a rotating shaft (22) integrally formed with a rear of the body (21).

The main body (20) of the grinding tool fixture (200) is turned, heat-treated, and then straightened.

Advantageous Effects

Therefore, according to the present invention, a grinding tool for a grinder can be conveniently attached and detached by reciprocating a sleeve such that a separate working tool or fastener is not required, the grinding tool can be immediately replaced even during use of the grinder, and straightness is ensured such that precise processing is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a grinding tool fixture according to the present invention.

FIG. 2 is a photograph of a state in which a grinding tool is coupled to the grinding tool fixture according to the present invention.

FIG. 3 is a photograph of an exploded state of the grinding tool fixture according to the present invention.

FIG. 4 is a photograph of a state in which a rotating shaft is integrally formed with a rear of the grinding tool fixture according to the present invention.

FIG. 5 is a photograph of a cap of the grinding tool fixture according to the present invention.

FIG. 6 is a photograph of a sleeve of the grinding tool fixture according to the present invention.

FIG. 7 is a photograph of a state in which a bearing is coupled to a bearing groove of the grinding tool fixture according to the present invention.

FIGS. 8 and 9 are detail views of a grinding tool according to the present invention (A and A′ are detailed side views of a quadrangular protrusion).

FIG. 10 is a cross-sectional view of a tool mounted at a tool post for a computer numerical control (CNC) lathe according to the present invention.

FIG. 11 is a photograph of a cross-sectional view taken along line A-A′ of FIG. 10 viewed from the right.

FIG. 12 is a photograph of the cross-sectional view taken along line A-A′ of FIG. 10 viewed from the left.

FIG. 13 is a view illustrating examples of processing tools according to the present invention.

FIG. 14 is a cross-sectional view of a tool.

Detailed Description <Description of reference numerals of main parts in the drawings> 1: Grinding tool 1-1: Grinding material 1-2: Grinding material holder 1-2a: Front horizontal part 1-2b: Inclined part 1-2c: Step 1-2d: Rear horizontal part 1-2e: Circular groove 1-2f: Quadrangular protrusion 1-2g: Chamfer 20: Main body 21: Body 21-1: Protrusion 21-2: Insertion groove 21-3: Bearing groove 21-4: Quadrangular groove 22: Rotating shaft 30: Cap 40: Sleeve 50: Coil spring 60: Bearing 200: Grinding tool fixture 100: Tool mounted at tool post for CNC lathe 110: Body 111: Portion B (inner wall) of body 112: Ring protrusion 120: Fixing part 130: Rotary body 131: Processing tool 132: Inclined surface 133: Flat surface 134: Wing part 140: Hammer protrusion 141: Spring 142: Case 143: Bolt 151: Retainer 152: Bearing 152-1: Front bearing 152-2: Central bearing 152-3: Rear bearing 153: Snap ring 153-1: Front snap ring 153-2: Rear snap ring 154: Washer

EMBODIMENTS

The present invention relates to a method of manufacturing a main body of a grinding tool fixture, a grinding tool fixture 200 having a cap 30 at a front, a sleeve 40 and a coil spring 50 consecutively connected, and a main body 20 connected at a rear, and the main body 20 having a body 21 and a rotating shaft 22 integrally formed with a rear of the body 21.

The main body 20 of the grinding tool fixture 200 is turned, heat-treated, and then straightened.

Further, after the straightening, turning is re-performed on an inclined part.

Further, a plurality of bearing grooves 21-3 are formed at an outer circumference of a front part of the body 21, a bearing 60 is inserted into the bearing groove 21-3 and fixes a grinding tool 1, a diameter of the bearing groove 21-3 is smaller than that of the bearing 60, the bearing 60 is unable to be detached from the bearing groove 21-3 toward a center of an inner diameter of the shaft and is detached out of the inner diameter of the shaft, and the coil spring 50 is installed between the sleeve 40 and the body 21 and pushes the sleeve 40 forward.

Further, the body 21 has a circular insertion groove 21-2 formed therein at a rear, a quadrangular groove 21-4 smaller than the insertion groove 21-2 extends from a rear surface of the insertion groove 21-2, and the body 21 and the rotating shaft 22 are integrally formed such that eccentricity does not occur during rotation, and quality of a processed product is improved.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a grinding tool fixture according to the present invention, FIG. 2 is a photograph of a state in which a grinding tool is coupled to the grinding tool fixture according to the present invention, FIG. 3 is a photograph of an exploded state of the grinding tool fixture according to the present invention, FIG. 4 is a photograph of a state in which a rotating shaft is integrally formed with a rear of the grinding tool fixture according to the present invention, FIG. 5 is a photograph of a cap of the grinding tool fixture according to the present invention, FIG. 6 is a photograph of a sleeve of the grinding tool fixture according to the present invention, FIG. 7 is a photograph of a state in which a bearing is coupled to a bearing groove of the grinding tool fixture according to the present invention, and FIGS. 8 and 9 are detail views of a grinding tool according to the present invention.

Conventionally, when a grinding tool is fitted into a front portion, a manual tool is used to widen an inlet through which the grinding tool is inserted, and then the grinding tool is fixed and used. In the present invention, a sleeve of a grinding tool fixture is pulled backward, a grinding tool is inserted thereinto, and then the sleeve pulled backward is moved forward to fix the grinding tool.

As a method of detaching the grinding tool, the sleeve of the grinding tool fixture is pulled backward, the grinding tool is detached, and then the sleeve pulled backward is moved forward to detach the grinding tool.

Elements of the grinding tool fixture 200 include the cap 30 at the front, the sleeve 40 and the coil spring 50 consecutively connected, and the main body 20 connected at the rear, and the main body 20 includes the body 21 and the rotating shaft 22 formed at the rear of the body 21

The cap, the sleeve, and the main body are formed of a chrome molybdenum steel (SCM) material, and SCM 415 material is mainly used.

The cap 30 has a hole formed at a center and is manufactured in two stages such that a step is formed and a diameter is gradually smaller toward a rear end.

The rear end of the cap is inserted into the sleeve therebehind, a screw part whose diameter is equal to an inner diameter of the cap 100 is formed, and the screw part is coupled to a front end of the body protruding forward inside the sleeve.

The sleeve is coupled to the rear of the cap, wherein the sleeve is formed in a cylindrical shape and has a groove formed at an outer circumference thereof to be easily grasped.

The sleeve is formed such that an inner diameter thereof is smaller at the rear than the front and allows a front end of the coil spring 50 to be seated.

The body 21 has a front end disposed inside the sleeve and a protrusion 21-1 formed at a middle, wherein the protrusion is formed to have a larger diameter than that of the front end of the body.

A rear end of the rotating shaft 22 formed behind the body 21 has a screw part formed thereat and is coupled to the grinder.

Further, instead of the screw part formed at the rear end of the rotating shaft, the rotating shaft may be formed in a polygonal shape and coupled to the grinder.

The body has the circular insertion groove 21-2 formed therein at the rear.

A portion in which the insertion groove is formed is up to a front end of the protrusion.

The quadrangular groove 21-4 in the quadrangular shape further extends from the rear end of the insertion groove, and a quadrangular shape at an end of the grinding tool is coupled to the quadrangular groove.

The quadrangular groove is formed to be smaller than the insertion groove.

A front portion of the body has three bearing grooves 21-3 formed at an outer circumference thereof, and the bearing 60 is inserted into the bearing groove to fix the grinding tool.

A ball bearing is used as the bearing.

Because a diameter of the bearing groove is smaller than that of the bearing, the bearing is unable to be detached from the bearing groove toward a center of an inner diameter of the shaft and may only be detached out of the inner diameter of the shaft.

The coil spring is installed between the sleeve and the body.

The coil spring 50 is installed between a rear portion of the inner diameter of the sleeve and a front portion of the protrusion of the body to always push the sleeve forward.

The body 21 has the bearing inserted into an outer circumferential surface thereof, and the bearing fixes the grinding tool. Three bearings are appropriate.

Therefore, the grinding tool is mounted at the front end of the grinding tool fixture, and the rear end of the grinding tool is processed to have a quadrangular cross-section so that the quadrangular portion is coupled to the quadrangular groove of the grinding tool fixture and rotates.

More specifically, the grinding tool includes a grinding material 1-1 and a grinding material holder 1-2 formed at a rear end of the grinding material.

The grinding material holder includes a front horizontal part 1-2 a, an inclined part 1-2 b, a step 1-2 c, a rear horizontal part 1-2 d, a circular groove 1-2 e, and a quadrangular protrusion 1-2 f consecutively formed from the front toward the rear.

The front horizontal part has a cylindrical shape, the inclined part is formed behind the front horizontal part, and the inclined part is formed to have a diameter gradually increasing from the rear toward the front.

The step is formed behind the inclined part, the rear horizontal part is formed behind the step, and the rear horizontal part is formed to have a smaller diameter than that of the front horizontal part.

The circular groove is formed behind the rear horizontal part. The circular groove is formed along the outer circumference of the grinding material holder, and the grinding tool is coupled or detached when a force is applied to the circular groove from the bearing of the grinding tool fixture.

The quadrangular protrusion processed to have a quadrangular cross-section is formed behind the circular groove.

A chamfer 1-2 g is formed at each corner of the quadrangular protrusion for the quadrangular protrusion to be easily coupled to the quadrangular groove of the grinding tool fixture.

Because the inclined part of the grinding material holder and the ring-shaped step are formed at corresponding positions in the body, eccentricity does not occur when the grinding material holder is coupled to the grinding tool fixer.

The cap, the sleeve, and the main body of the grinding tool fixture of the present invention are turned on a computer numerical control (CNC) lathe and are carburized and heat-treated.

Particularly, a method of processing a main body of the grinding tool fixer, which is the technical gist of the present invention, will be described in detail.

The main body of the grinding tool fixer is processed by turning a material thereof according to a shape shown in FIG. 4.

In processing the quadrangular groove of the body, the circular groove is processed first, and then the quadrangular groove is processed. The circular groove is circularly drilled first, and when a length of one side of a quadrangular cross-section of the quadrangular groove is 5.1 mm, drilling is performed so that a diameter is 5 mm smaller. Then, the quadrangular groove is processed. Because the quadrangular protrusion of the grinding material holder coupled to the quadrangular groove has the chamfer formed at each of the corners, the quadrangular protrusion is easily coupled to the quadrangular groove. Here, a diagonal length of the quadrangular groove is about 6.1 mm.

Here, a gap of about 0.2 mm is formed between an end of the quadrangular protrusion of the grinding material holder and a bottom surface of the quadrangular groove.

Then, a hole is processed using a drill and an end mill.

Then, a heat treatment step is performed. A carburized heat treatment method is used for the heat treatment so that a hardness of HRC55 is achieved. The carburizing temperature is in the range of 830 to 850° C. The carburizing time is about 3 hours 20 minutes to 3 hours 40 minutes.

Then, straightening is performed. The main body that is bent like a bow due to being heat treated is put in a straightening mold and pressed to be straightened such that a straightness tolerance is within 5/100.

Because deformation occurs after the heat treatment, the inclined part is separately grinded after the heat treatment. This is to compensate for straightness.

Here, the CNC lathe uses an outer diameter collet chuck exclusive therefor, and an inclined surface of a corresponding tool also accurately corresponds to a predetermined angle, 15°.

In the present invention, the inclined part of the grinding material holder and the ring-shaped step are formed at corresponding positions. Therefore, after straightness of the quadrangular groove of the body is determined, the inclined angle is set as 15° when the straightness tolerance is within the predetermined tolerance, 5/100, and the inclined angle is set to be smaller than 15° to compensate for the straightness when the straightness tolerance deviates from the predetermined tolerance, 5/100, and increases. When the inclined angle becomes smaller than 15°, a length tolerance increases when a front end of a tool is worn out, and a service life of the tool increases.

Because the inclined angle of the front end of the tool may be set to be large, the length tolerance decreases even when the front end of the tool is worn out, and the service life of the tool increases.

FIG. 10 is a cross-sectional view of a tool mounted at a tool post for a CNC lathe according to the present invention, FIG. 11 is a photograph of a cross-sectional view taken along line A-A′ of FIG. 10 viewed from the right, FIG. 12 is a photograph of the cross-sectional view taken along line A-A′ of FIG. 10 viewed from the left, FIG. 13 is a view illustrating examples of processing tools according to the present invention, and FIG. 14 is a cross-sectional view of a tool.

The tool mounted at the tool post for the CNC lathe has one side fixed to the tool post and the other side fixed to an object to be processed to be rotated. The tool mounted at the tool post for the CNC lathe includes a fixing part fixed to the tool post, a body coupled to the front of the fixing part, and a rotary body mounted at the body and configured to process a material.

The body is formed in a cylindrical shape and has an open front portion and a space portion formed therein. The rotary body is mounted in the space portion.

That is, the rotary body is coupled to the front of the body, and the fixing part is coupled to the rear of the body.

The fixing part is formed in a tubular structure that may be mounted at the tool post for the CNC lathe. Because the tubular shape is already well-known, a detailed description thereof will be omitted.

As an example, the body includes a front body and a rear body which are separate from each other, a screw surface is formed at a portion at which the two bodies are coupled to facilitate attachment/detachment of the bodies, the pair of bodies are screw-fastened, a ring-shaped ring protrusion is formed at an inner circumference of the front body, and a bearing is disposed in front of and behind the ring protrusion for the rotary body to be stably rotated inside the front body.

The rotary body is mounted inside the body and rotated. The rotary body is formed in a cylindrical shape, a ring-shaped wing part is formed at a center of an outer circumference of the rotary body, and a bearing is disposed in front of and behind the wing part or the rotary body to be stably mounted and rotated inside the body.

A coupling groove, whose perpendicular cross-section is circular, is formed at a front surface of the rotary body, and a processing tool having a polygonal shape is mounted at the coupling groove.

A perpendicular cross-section at a front side of the processing tool is formed in a shape into which an object to be processed is desired to be processed. After the processing tool is forcibly fitted into a hole formed in an object to be processed, a force of forcibly pushing the object to be processed is applied to the hole, thereby forging the object to be processed.

In the present invention, as an example, the processing tool is formed in a hexagonal shape. The processing tool may also be formed in various other shapes such as triangular, quadrangular, and stellar.

As illustrated in FIG. 12, the perpendicular cross-section of the rotary body is formed in a circular shape, a plurality of locking steps are consecutively formed in a circumferential direction at an edge of a rear surface, and inclined surfaces and flat surfaces are repeatedly formed.

As illustrated in FIG. 10, a hammer protrusion is installed behind the rotary body to come in contact with the rear surface, the hammer protrusion is formed in a cylindrical shape, a semi-circular protrusion is formed at a front surface of the hammer protrusion, and a locking protrusion is formed at an outer circumference at a central portion for a spring to be stably coupled.

The spring is coupled to the rear of the hammer protrusion. One side of the spring is fixed to an inner wall of the body, and the other side thereof is coupled to the hammer protrusion.

As illustrated in FIG. 10, as an example in which the hammer protrusion and the spring are mounted, the hammer spring and the spring may be inserted into a case, and preferably, the case has an open front portion so that the hammer protrusion and the spring may be inserted thereinto.

The spring used in the present invention is a compression spring, which is a spring that resists a compressive force.

Because the hammer protrusion is coupled to the body, and the rotary body is rotated, the hammer protrusion continuously comes in contact with the inclined surfaces and the flat surfaces formed at the rear surface of the rotary body.

The rotation of the rotary body occurs as follows. Because the tool mounted at the front surface of the rotary body is forcibly fitted into the hole in the object to be processed, as the object to be processed is rotated, the rotary body as well as the tool are rotated at the same rotational speed as that of the object to be processed.

As the rotary body is rotated, the hammer protrusion comes in contact with one of the plurality of inclined surfaces, and the hammer protrusion is pushed backward.

A rotational direction of the rotary body is as follows. The rotary body rotates in a direction in which the hammer protrusion comes in contact with the highest point of the inclined surface from the lowest point thereof, and then, as the hammer protrusion comes in contact with one of the flat surfaces from the highest point of the inclined surface, the hammer protrusion hits the flat surface of the rotary body due to a restoration force of the spring coupled to the rear of the hammer protrusion.

As the hammer protrusion hits the rear surface of the rotary body, an inner shape of the hole in the object to be processed becomes a polygonal shape due to the tool forcibly fitted into the hole.

That is, the hammer protrusion is reciprocated, and accordingly, the tool is periodically forcibly pushed into the hole in the object to be processed, thereby processing the object to be processed.

Because the rotary body is seated inside the body and coupled thereto while the body is fixed and only the rotary body is rotated, a plurality of coupling members are coupled to the outer circumferential surface of the rotary body to facilitate rotation of the rotary body.

In the present invention, a retainer, a front bearing, a snap ring, a washer, a pair of central bearings, a rear bearing, and a snap ring are consecutively installed at the outer circumferential surface of the rotary body from the front toward the rear.

The retainer is a part formed in a ring shape and fitted for balls or rolls of a ball bearing or a roller bearing to always maintain the same interval therebetween, the bearings are parts that reduce frictional resistance when the shaft is rotated to facilitate the rotation, the snap rings are fastening parts that act as springs to prevent parts from falling out, and the washer serves to disperse a pressure with a ring shape.

The plurality of coupling members used in the present invention may be rearranged any time according to convenience of a user.

Therefore, the tool mounted at the tool post for the CNC lathe is mounted at the tool post and forges a wrench groove at an end surface of a shaft and the like, process efficiency and production efficiency may be improved due to the convenient processing process, and a defect rate may be reduced.

Therefore, according to the present invention, the grinding tool for a grinder can be conveniently attached and detached by reciprocating a sleeve such that a separate working tool or fastener is not required, the grinding tool can be immediately replaced even during use of the grinder, and straightness is ensured such that precise processing is possible. 

What is claimed is:
 1. A method for manufacturing a main body of a grinding tool fixture, the grinding tool fixture having a cap at a front, a sleeve and a coil spring consecutively connected, and a main body connected at a rear, the main body having a body and a rotating shaft integrally formed with a rear of the body, and the main body being turned, heat-treated, and then straightened, the method comprising: after straightening the main body, turning the main body on an inclined part of the grinding tool fixture; forming a plurality of bearing grooves at an outer circumference of a front part of the body; fixing a grinding tool by inserting a bearing into a bearing groove from the plurality of bearing grooves, wherein a diameter of the bearing groove is smaller than that of the bearing, the bearing is unable to be detached from the bearing groove toward a center of an inner diameter of the shaft and is detached out of the inner diameter of the shaft, and the coil spring is installed between the sleeve and the body and pushes the sleeve forward; forming a circular insertion groove at a rear of the body, wherein a quadrangular groove smaller than the insertion groove extends from a rear surface of the insertion groove, and the body and the rotating shaft are integrally formed such that eccentricity does not occur during rotation, and quality of a processed product is improved; mounting the grinding tool at a front end of the grinding tool fixture; processing the rear end of the grinding tool to have a quadrangular cross-section so that a quadrangular protrusion is formed; forming a chamfer at each corner of the quadrangular protrusion for the quadrangular protrusion to be easily coupled to the quadrangular groove of the grinding tool fixture; wherein the grinding tool includes a grinding material and a grinding material holder formed at a rear end of the grinding material, and the grinding material holder includes a front horizontal part, an inclined part, a step, a rear horizontal part, a circular groove, and a quadrangular protrusion consecutively formed from the front toward the rear of the grinding material holder; and wherein the front horizontal part includes a cylindrical shape, the inclined part is formed behind the front horizontal part, and the inclined part is formed to have a diameter gradually increasing from the rear toward the front, the step is formed behind the inclined part, the rear horizontal part is formed behind the step, and the rear horizontal part is formed to have a smaller diameter than that of the front horizontal part, the circular groove is formed behind the rear horizontal part, the circular groove is formed along the outer circumference of the grinding material holder, and the grinding tool is coupled or detached when a force is applied to the circular groove from the bearing of the grinding tool fixture.
 2. A grinding tool fixture comprising: a cap at a front; a sleeve and a coil spring that are consecutively connected; and a main body connected at a rear, the main body having a body and a rotating shaft formed behind the body; wherein: the body has a circular insertion groove formed therein at a rear, a quadrangular groove smaller than the insertion groove extends from a rear surface of the insertion groove, and the body and the rotating shaft are integrally formed such that eccentricity does not occur during rotation, and quality of a processed product is improved; the body has a front end disposed inside the sleeve and a protrusion formed at a middle, a bearing groove is formed at an outer circumference of a front part of the body, and a bearing is inserted into the bearing groove and fixes a grinding tool so that the sleeve is pushed forward; the grinding tool is mounted at a front end of the grinding tool fixture and includes a grinding material and a grinding material holder formed at a rear end of the grinding material, the grinding material holder includes a front horizontal part, an inclined part, a step, a rear horizontal part, a circular groove, and a quadrangular protrusion consecutively formed from the front toward the rear, and a chamfer is formed at each corner of the quadrangular protrusion for the quadrangular protrusion to be easily coupled to the quadrangular groove of the body; the grinding tool includes a grinding material and a grinding material holder formed at a rear end of the grinding material, and the grinding material holder includes a front horizontal part, an inclined part, a step, a rear horizontal part, a circular groove, and a quadrangular protrusion consecutively formed from the front toward the rear; the front horizontal part has a cylindrical shape, the inclined part is formed behind the front horizontal part, and the inclined part is formed to have a diameter gradually increasing from the rear toward the front, the step is formed behind the inclined part, the rear horizontal part is formed behind the step, and the rear horizontal part is formed to have a smaller diameter than that of the front horizontal part, the circular groove is formed behind the rear horizontal part, the circular groove is formed along the outer circumference of the grinding material holder, and the grinding tool is coupled or detached when a force is applied to the circular groove from the bearing of the grinding tool fixture. 